258 A Monograph of the Mi/xofjastres. 



DiACHAEA, Fr. 



Wall of sporangium without lime externally, but sometimes 

 containing scattered granules on its inner surface, tliin, usually 

 with metallic tints ; columella either thick and elongated, rigid 

 with amorphous lumps of lime, or more or less rudimentary 

 and represented by an accumulation of lime at base of spor- 

 angium; capillitium forming a dense net, springing from the 

 columella or base of sporangium, threads usually coloured, 

 without lime, thickest at the point of origin. 



Diachaca, Fries, Syst. Orb. Veg., i., p. 143 ; Fr., Syst. Myc, 

 iii., p. 155; Kost., Mon., p. 190; Cooke, Myx. Brit., p. 44; 

 Sacc, Syll, p. 387. 



Although placed in a different order by Rostafinski, Lami^ro- 

 dcrma approaches the present genus so closely, that it is open 

 to doubt whether the two genera, as at present understood, 

 should not be merged into one. The generic diagnoses of the 

 two, as given by Rostafinski, illustrate the two poles of the 

 genus in the larger sense, and read very distinct, but when a 

 complete sequence of the species included in the two genera 

 are examined, then the difficulty of " drawing the line " becomes 

 only too apparent, and the only character that remains is, the 

 presence of lime in the columella and stem iu Diachaca^ and 

 its absence in Lam'proderma. In Laminodcrma violacca, Fr., 

 the columella is filled with large vesicles as in Trichia fcdlax, 

 and in Lampo'odcrma sulweneus, B., well-developed granules of 

 lime are by no means rare in the threads of the capillitium ; 

 lime is by no means always absent from the capillitium of 

 several species of Stemonitis, and other genera belonging to 

 the order Amaurochacte, the most important feature of which 

 consists in the absence of lime. 



DiacJmea is as far from being a typical member of the 

 Calcarcae, owing to the entire absence of lime on the surface 

 of the wall of the sporangium, as it is from being ty])ical of 

 the Amaurochaetcae on account of the lime contained in the 

 columella and stem. 



Distrih. Europe; United States; W. Indies; Brazil; S.Africa; 

 India; Australia; New Zealand. Species 5. 



